The Skinny: The HydroPak replaces batteries and generators with cartridges that can sit on the shelf for ages, activated with water for 12 hours of power. They're quiet with zero emissions, and each $20 dry cartridge cranks out a lot more than any battery can—400 Watts through an AC outlet and two USB ports. The Catch: The device costs $400 and it's still in beta, although that's a lot cheaper than other fuel cell products. But it's a real product, rolling out first next week at CES, and samples will be available in February. [Millennium Cell (pdf)]